Support for reheater and superheater elements

ABSTRACT

A support for reheater and superheater elements of a vapor generator. A plurality of vertically oriented tube panels define a rectangular enclosure in which the elements are contained. Pairs of horizontal tube sections extend across the face of opposite panels of the enclosure sufficiently spaced from the panels to support the elements. These sections are continuations of riser tubes which occupy positions along opposite sides of the panels. Each tube section is bent inwardly from the plane of its panel, at one side of the panel, and then is bent back into the plane of the panel at the opposite side, after traversing the face of the panel. It occupies a position vacated as a result of traverse of the face of the panel by the companion tube section of the tube pair.

United States Patent [191 Beckman Oct. 30, 1973 Eugene B. Beckman, Rockaway Twp., NJ.

[73] Assignee: Foster Wheeler Corporation,

Livingston, NJ.

[22] Filed: Jan. 20, 1972 [21] Appl. No.: 219,264

[75] Inventor:

Primary Examiner-Kenneth W. Sprague Attorney-1ohn Maier, III et al.

[57] ABSTRACT A support for reheater and superheater elements of a vapor generator. A plurality of vertically oriented tube panels define a rectangular enclosure in which the elements are contained. Pairs of horizontal tube sections extend across the face of opposite panels of the enclosure sufficiently spaced from the panels to support the elements. These sections are continuations of riser tubes which occupy positions along opposite sides of the panels. Each tube section is bent inwardly from the plane of its panel, at one side of the panel, and then is bent back into the plane of the panel at the opposite side, after traversing the face of the panel. It 0ccupies a position vacated as a result of traverse of the face of the panel by the companion tube section of the tube pair.

9 Claims, 4 Drawing Figures PATENTEUBCI 30 1975 SHEET 2 0F 2 SUPPORT FOR REHEATER AND SUPERHEATER ELEMENTS DESCRIPTION OF THE INVENTION The present invention relates to vapor generators, and particularly to a fluid support arrangement for heat absorption elements of the generator, such as the generator superheater and reheater.

The present invention is particularly applicable to natural circulation peaking generators of the type having a boxtype enclosure, and superheater and reheater elements immediately above the furnace portion of the enclosure, and will be described with reference thereto, although it will be appreciated that the invention has other applications, for instance, support of reheater and superheater elements in a once-through generator.

A furnace enclosure of the box-type with which the present invention is concerned, is rectangular in crosssection and has essentially the same outside dimensions for the entire elevation of the enclosure. The lower part of the enclosure constitutes the furnace Above the furnace, the tubes of the rear wall of the enclosure are bent inwardly from the plane of the wall and them upwardly to divide the enclosure at this elevation into a constricted front gas pass and a rear heat recovery area. Near the top of the enclosure, the rear wall tubes are spread apart to provide a gas exit for the flow of gas from the front pass to the heat recovery area.

The heat recovery area accommodates an economizer and a portion of a reheater element. The front pass accommodates the remainder of the reheater element, a finishing superheater element and a primary superheater element, the latter being disposed closest to the furnace of the generator.

The reheater and superheater elements are a plurality of side-by-side vertically oriented platens of nestedreturn bend or looped tubes. They are positioned between the front and rear walls of the enclosure in the front pass. Heretofore, such platens have been supported by stringer support tubes extending from the top of the enclosure downwardly, or by lugs welded onto support tubes in the front and rear walls of the enclosure. I

The shape of the enclosure and reduced dimensions of the front gas pass cause the pass to be an area of intense heat. This has resulted in certain problems with the prior support arrangements. For instance, in the case of stringer supports, high heat pick-up and load may cause a high degree of differential expansion in the supports which has to be accommodated. In addition, the stringer supports are fluid cooled. Being in a high heat absorption area of the generator, there is a high enthalpy pick-up in the stringers. This has made it difficult to assimilate the fluid exiting from the stringers into other circuitry of the generator without flow upset.

Accordingly, it is an object of the present invention to provide an improved support arrangement for reheater and superheater elements of a generator.

It is also an object of the present invention to provide an improved fluid cooled support arrangement for heating elements positioned in an area of intense heat of a generator.

A further object of the present invention is to provide a support for heating elements of a generator utilizing sections of tubes making up walls of the generator.

Another object of the present invention is to overcome the disadvantages experienced with prior reheater and superheater support arrangements.

Other aspects of the invention, and objects and advantages thereof will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but several of the various ways in which the principles of the invention may be employed.

The figures herein illustrate preferred forms of the support arrangements embodying the present invention, in which:

FIG. 1 is a section elevation view of a vapor generator in accordance with the concepts of the present invention;

FIG. 2 is a perspective elevation view of a support panel in accordance with the concepts of the present invention;

FIG. 3 is an enlarged section elevation view of a portion of the support arrangement of FIG. 2 illustrating aspects of the present invention; and

FIG. 4 illustrates an embodiment in accordance with the concepts of the present invention.

Referring to the drawings, FIG. 1 illustrates a natural circulation peaking-type vapor generator 12 having a box-type enclosure 14. The generator has front and rear walls 16 and 18 which are made up of a plurality of parallel vertically oriented tubes welded together along their lengths to provide a fin-tube, all welded, gas tight construction. The lower portion of the enclosure constitutes the generator furnace 20. The furnace is heated by a plurality of burners 22, preferably gas or oil fired.

About two-thirds of the distance between the bottom and top of the enclosure, the rear wall tubes are bent inwardly at 24 and then upwardly at 26 to provide a division wall 28 dividing the enclosure, at the top, into a constricted front gas pass 30, above the furnace 20, and a heat recovery area 32 occupying the remainder of the enclosure. The rear wall or division wall tubes, near the top of the enclosure, are separated to provide a gas exit 34 which permits the flow of gas from the front pass 30 to the heat recovery area 32. Roof tubes 37 extending across the top of the front pass 30 and heat recovery area 32 are bent downwardly at 38 to complete the rear side 39 of the enclosure, lying in the same vertical plane as rear wall tubes 18. Near the bottom of the heat recovery area 32, the rear side tubes 39 are spread apart to provide a gas exit 40 leading to stack 42. The portion 44 of the rear wall 18, above the furnace, extending inwardly from the plane of the rear wall, between points 24 and 26, constitutes the heat recovery area floor.

An economizer 46 is housed within the heat recovery area 32, along with a part of reheater element 50, identified by the numeral 50a, above the economizer. The reheater element extends through the gas exit 34 into the front pass 30. The part of the reheater element in the front pass is identified by the numeral 50b. A finishing superheater element 54 is also positioned in the front pass 30, immediately beneath reheater element 50b, and a primary superheater element 56 is positioned beneath the finishing superheater element. Both of these last mentioned elements are contained totally within the front pass.

The present invention is concerned primarily with support of the primary superheater element 56, the finishing superheater element 54 and the portion 50b of the reheater element.

Each of these elements comprises a plurality of adjacent platens which are coils of tubes extending between the front wall 16 of the enclosure and the division wall 28. FIG. 2 illustrates single platens of each of the elements, the lower platen 54a being part of the finishing superheater element. A large number of these platens, in spaced-apart side-by-side relationship, are employed for each element. The platens are located in vertical planes, and each platen comprises a pair of return-bend or looped tubes which are in nested relationship for parallel flow through the tubes.

In accordance with the concepts of the present invention, tubes of the front and rear walls of the enclosure provide the support for the reheater and superheater elements.

FIG. 2 illustrates a portion of the front wall of the enclosure. The figure shows only a single panel 58 of the front wall. The generator illustrated in FIG. 1 has a capacity of approximately 800 megawatts. The depth of the enclosure, that is from the front wall to the rear wall is about 40 feet. The width of the enclosure between thesides is about 75 feet. To make these walls economically, a plurality of narrower panels, for instance about feet in width, are made and then are field connected together. In the generator of FIG. 1, about seven panels will be employed across the width of the enclosure and about four on each side. The embodiment of FIG. 2 represents only one of these panels in the front wall 16 of the enclosure.

In FIG. 2, inlet header 59 is near the bottom of the generator. The area of the panel immediately above the header is part of the furnace enclosure. Parts of the panel have been broken away, in the figure, so that the full height of the panel is not represented.

The panel illustrated in FIG. 2 has a plurality of shelves at three spaced apart elevations of the panel. The shelves are identified by the numerals 60, 62 and 64. Each shelf in the panel is substantially horizontally oriented. They are positioned at several elevations at the height of the gas pass 30. The same number of shelves also are provided in the opposite division wall 28, at or about the same elevations. The lower shelves 60 of the front and divison walls support the primary superheater platens. The middle shelves 62 support the finishing superheater platens and the upper shelves 64 support the portions 50b of the reheater platens.

It should be understood that although the drawing shows three shelves only, a greater or lesser number of shelves can be provided depending upon the number of elements to be supported.

Each shelf of a panel is constructed of a pair of tubes which are sections or extensions of riser tubes in the tube panel, the numerals 66 and 68 indicating the tube sections for the lower shelf 60. These tubes sections, and also those of the intermediate and upper shelves, horizontally traverse the face of the panel spaced a sufficient distance from the panel to support the reheater and superheater elements.

Looking outward at the panel (in FIG. 2), the numerals 1, 2 and 3 identify three positions adjacent the left hand side of the panel, and the numerals 4, 5 and 6 identify three tube positions adjacent the right hand side of the panel. At the elevation of the first shelf 60 of the panel, the riser tube in position 1 is bent inwardly, into the gas pass, from the plane of the panel, and then to the right to traverse the face of the panel forming tube section 66. The riser tube in position 6 also is bent inwardly at this elevation from the plane of the panel, and then is bent to the left to traverse the face of the panel forming tube section 68. The two tube sections are essentially contiguous with each other in the traverse. On the right-hand side of the panel, the tube section 66 (which previously occupied position 1) is bent back into the plane of the panel to occupy a a position which was vacated as a result of the tube of position 4 being moved diagonally to the position 5. Similarly, the tube of position 6 on the left-hand side is bent outwardly back into the plane of the panel to occupy a position vacated as a result of the traverse by the tube of position 3, being moved diagonally to position 2.

In the particular embodiment illustrated, the tube of position 5 on the right-hand side of the panel, at the elevation of the lower shelf, moves to the right to occupy position 6 now vacated. Similarly, the tube of position 4 moves to the right to occupy the position previously occupied by the tube of position 5. Re-entry of tube 1 then is into position 4. Similarly, on the left-hand side of the panel, the tube of position 2 is moved to the left to occupy vacated position 1. The tube of position 3 occupies vacated position 2, and the traversing tube of position 6 then occupies vacated position 3.

The second or intermediate shelf is made up of tube sections 70 and 72 which again are extensions of the riser tubes occupying positions 1 and 6 in the area of the panel immediately below the shelf, except that these riser tubes, in the lower or furnace portion of the enclosure occupied tube positions 2 and 5. Similarly, the upper shelf is composed of tube sections 74 and 76 which are extensions of riser tubes from positions 1 and 6, except that in the lower part of the enclosure, the riser tubes occupied positions 3 and 4. A significant characteristic of the invention is that the tube sections of the multiple shelves are all in communication with risers which, in the areas immediately beneath the shelves, are at the same positions in the panel, preferably positions 1 and 6 along the sides of the panel. In this way the shelves are all of the same width, and essentially equal to the width of the panel. Thus, where the generator enclosure is made up of a plurality of side-byside panels, the shelf support is substantially continuous across the full width of the enclosure.

The routing pattern of one of the riser tubes, for instance the riser tube occupying position 2 in the lower furnace portion of the generator further exemplifies the invention. At the elevation of the lower shelf, the tube shifts to position 1. At the elevation of the intermediate shelf, it traverses the panel consituting one of the support tube sections, re-entering the panel at position 4. Finally, at the elevation of the upper shelf, it shifts to the right to occupy position 5.

A primary advantage of the invention is that the supports for the superheater and reheater elements are fluid cooled. Since the support tube sections extend only the width of the individual panels, for instance about 10 feet, they are not subjected to undue stresses. In this respect, the sections can be made thicker for adequate strength; that is, with thicker walls. As a further advantage, the shelves can be shop fabricated during construction of the panels. This avoids the cost normally associated with field fabrication.

Other advantages accrue from the invention. Stringers or fluid cooled supports for reheater and superheater elements are subjected to considerable heat input, particularly in a generator of the box-type with which the present invention is primarily concerned. In the present invention, the shelves are all constructed of sections from different riser tubes of a tube panel, and each tube section is in length equal only to about the width of the panel, about feet in the embodiment illustrated. In the example illustrated, 12 different tube sections of short length are actually involved in the construction of three shelf pairs (per panel width), and the extra heat input is correspondingly divided and minimized per tube.

As still another advantage, the invention maintains the structural integrity of the enclosure. It will be recalled that the panel is of the fin-tube type construction in which the tubes are welded together along their lengths so that the panels are essentially gas-tight. By the invention, the tube pattern across the face of the panel is essentially continuous without large areas which have to be bridged by fins: nor are there any large gaps between successive riser tubes along a particular tube centerline or position which would adversely affect the strength of the top supported panels.

If desired, the shelf tube sections could be fed with separate feeders and risers to insure adequate circulation, or they can be made larger in outside diameter for the purpose of insuring adequate circulation. In this respect the invention is particularly useful in a natural circulation generator in that there are no downflow tube sections, and resistances to flow in particular risers are minimized.

Relative motion between the shelf supports and the reheater and superheater elements is necessary. In particular, it is necessary to accommodate longitudinal expansion of the superheater and reheater platens. This can be accomplished in accordance with the present invention by placing a pair of rings 80 (FIG. 3) around the support tubes at the transverse. positions of the reheater and superheater elements. The rings permit longitudinal expansion, but prevent sideways movement of the elements.

The superposed nested tube lengths of the platens are spaced and supported relative to one another by a plurality of spacers 82 between the tube lengths. These spacers preferably are spaced to seat between the tubes and are not welded to the tubes.

FIG. 4 shows a method of forming the superheater and reheater element supports and bracing the supports with one of the crossing tubes. In this embodiment, the tube support section which is an extension of the tube at position 6 in the panel, is pulled out of the panel at an elevation somewhat lower than the elevation of the shelf, and is angled upwardly and inwardly with respect to the plane of the panel to provide an angled brace 84 for the support shelf. On the opposite or left-hand side of the panel, the tube section is then angled back into the plane of the panel entering the panel at an elevation somewhat above the elevation of the shelf to provide a second brace 86. In this embodiment, only one shelf 88 is provided, and each tube of the shelf occupies a position in the panel vacated by the companion tube of the shelf.

I, therefore, particularly point out and distinctly claim as my invention:

1. A vapor generator comprising a plurality of vertically oriented tubes defining an enclosure;

at least one tube element contained within the enclosure; I

support means for supporting said tube element;

said support means comprising a pair of tube sections of said enclosure which are bent inwardly from the plane of the enclosure and traverse a face of the enclosure at a distance spaced from the face, the tube sections being extensions of riser tubes in the enclosure which occupy spaced apart positions in the enclosure, the extensions traversing the face of the enclosure in opposite directions.

2. The vapor generator of claim 1 wherein said tube sections after traversing the face of the enclosure are bent outwardly back into the plane of the enclosure to occupy a position vacated as a result of the traverse of the face by the companion tube section of the pair of tube sections.

3. The generator of claim 2 wherein said tube element comprises reheater and/or superheater platens.

4. The generator of claim 3 wherein said enclosure is of the box-type including a constricted gas pass for said tube element immediately above the generator furnace.

'5. The generator of claim 2 wherein the support means comprises a pair of shelves on opposite sides of the enclosure, each shelf comprising one pair of said tube sections, the shelves being at essentially the same elevation in the enclosure, each tube section reentering the enclosure at the tube position vacated by the companion tube section of the pair.

6. A vapor generator comprising a plurality of vertically oriented tubes defining an enclosure;

a plurality of tube elements at different elevations supported within the enclosure;

a plurality of support means including first and second support means at different elevations for supporting said tube elements;

each said support means comprising a pair of tube sections of said enclosure which are bent inwardly from the plane of the enclosure and horizontally traverse the face of the enclosure at a distance spaced from the face;

the tube sections of the first support means being extensions of first riser tubes in the enclosure which occupy spaced apart positions in the enclosure, and the tube sections of the second support means being extensions of second riser tubes spaced apart in the enclosure and different from said first riser tubes;

the second riser tubes occupying the positions in the enclosure, in the expanse between the first and second support means, vacated by the first riser tubes.

7. A vapor generator comprising a plurality of vertically oriented panels defining a rectangular enclosure, each of said panels comprising a plurality of tubes welded together along their length to define a gas-tight construction;

a wall of said enclosure comprising multiple side-byside panels;

said enclosure defining a gas pass;

superheater and/or reheater tube elements contained within said pass, said elements comprising platens extending across the pass between opposite walls of the enclosure; support means for supporting said elements, said support means being in the form of shelves extending horizontally across the face of opposite panels of the enclosure; each shelf comprising a pair of tube sections bent inwardly from the plane of the panel and traversing the face of the panel at a distance spaced from the face, the tube sections being extensions of riser tubes in the panel which occupy positions along opposite sides of the panel. 8. The generator of claim 7 wherein each tube section after traversing the face of the panel is bent inwardly to the plane of the panel to occupy a position in the panel vacated as a result of traverse of the face of the panel by the companion tube section of said pair of tube sections.

9. The generator of claim 8 wherein each panel has a first shelf and a second shelf at an elevation spaced from and above the first shelf, the tube sections of the second shelf being extensions of a pair of riser tubes which occupied positions in the panel removed from the edges of the panel at elevations below the first shelf; said riser tubes at the elevation of the first shelf having been shifted to the edges of the panel to occupy the positions vacated by the riser tubes in communication with the tube sections of the first shelf. 

1. A vapor generator comprising a plurality of vertically oriented tubes defining an enclosure; at least one tube element contained within the enclosure; support means for supporting said tube element; said support means comprising a pair of tube sections of said enclosure which are bent inwardly from the plane of the enclosure and traverse a face of the enclosure at a distance spaced from the face, the tube sections being extensions of riser tubes in the enclosure which occupy spaced apart positions in the enclosure, the extensions traversing the face of the enclosure in opposite directions.
 2. The vapor generator of claim 1 wherein said tube sections after traversing the face of the enclosure are bent outwardly back into the plane of the enclosure to occupy a position vacated as a result of the traverse of the face by the companion tube section of the pair of tube sections.
 3. The generator of claim 2 wherein said tube element comprises reheater and/or superheater platens.
 4. The generator of claim 3 wherein said enclosure is of the box-type including a constricted gas pass for said tube element immediately above the generator furnace.
 5. The generator of claim 2 wherein the support means comprises a pair of shelves on opposite sides of the enclosure, each shelf comprising one pair of said tube sections, the SHELVES being at essentially the same elevation in the enclosure, each tube section re-entering the enclosure at the tube position vacated by the companion tube section of the pair.
 6. A vapor generator comprising a plurality of vertically oriented tubes defining an enclosure; a plurality of tube elements at different elevations supported within the enclosure; a plurality of support means including first and second support means at different elevations for supporting said tube elements; each said support means comprising a pair of tube sections of said enclosure which are bent inwardly from the plane of the enclosure and horizontally traverse the face of the enclosure at a distance spaced from the face; the tube sections of the first support means being extensions of first riser tubes in the enclosure which occupy spaced apart positions in the enclosure, and the tube sections of the second support means being extensions of second riser tubes spaced apart in the enclosure and different from said first riser tubes; the second riser tubes occupying the positions in the enclosure, in the expanse between the first and second support means, vacated by the first riser tubes.
 7. A vapor generator comprising a plurality of vertically oriented panels defining a rectangular enclosure, each of said panels comprising a plurality of tubes welded together along their length to define a gas-tight construction; a wall of said enclosure comprising multiple side-by-side panels; said enclosure defining a gas pass; superheater and/or reheater tube elements contained within said pass, said elements comprising platens extending across the pass between opposite walls of the enclosure; support means for supporting said elements, said support means being in the form of shelves extending horizontally across the face of opposite panels of the enclosure; each shelf comprising a pair of tube sections bent inwardly from the plane of the panel and traversing the face of the panel at a distance spaced from the face, the tube sections being extensions of riser tubes in the panel which occupy positions along opposite sides of the panel.
 8. The generator of claim 7 wherein each tube section after traversing the face of the panel is bent inwardly to the plane of the panel to occupy a position in the panel vacated as a result of traverse of the face of the panel by the companion tube section of said pair of tube sections.
 9. The generator of claim 8 wherein each panel has a first shelf and a second shelf at an elevation spaced from and above the first shelf, the tube sections of the second shelf being extensions of a pair of riser tubes which occupied positions in the panel removed from the edges of the panel at elevations below the first shelf; said riser tubes at the elevation of the first shelf having been shifted to the edges of the panel to occupy the positions vacated by the riser tubes in communication with the tube sections of the first shelf. 